I recommend the K-Lite Mega Codec Pack. When you install it you get Media Player Classic and it can play Quicktime, Real Media, DivX and all sorts of other formats without the need for other players. This means you don't need to install Quicktime, Real Player etc.
Some mirror links: (all the same file, just in case one server doesn't work)
http://dl.codecpack.nl/k/klmcodec137.exe
http://i1.edskes.com/k/klmcodec137.exe
http://i2.edskes.com/klmcodec137.exe
http://j1.edskes.com/klmcodec137.exe
http://j2.edskes.com/klmcodec137.exe
The homepage is actually:
http://home.hccnet.nl/h.edskes/finalbuilds.htm